MALIGNANT LYMPHOMA, B-LYMPHOBLASTIC LEUKEMIA/LYMPHOMA TYPE
Cytogenetic FISH studies: Negative for a BCR/ABL1 translocation
Introduction: B-Lymphoblastic lymphoma (B-LBL) is a neoplasm of the precursor B-cells. B-lymphoid proliferations are conventionally considered to be lymphoma rather than leukemia when there are mass lesions, and focal (<25%) or absent bone marrow and/ or peripheral blood involvement. The B lymphoblastic leukemia/ lymphoma are further subdivided in the 2008 WHO classification based on cytogenetic findings. B-LBL comprises only approximately 10% of all lymphoblastic lymphoma.
Site: The most frequently involved sites of B-LBL are skin, soft tissue, bone and lymph nodes. In contrast, T-LBL most commonly involves the mediastinum.
Clinical features: Most patients with B-LBL are asymptomatic with limited stage disease.
Morphology: B-lymphoblastic lymphoma is characterized by a diffuse or in lymph nodes, sometimes paracortical proliferation of cells. Mitotic figures may be common and there may be a starry sky appearance. The lymphoblasts can have a variable appearance ranging from more closely resembling small lymphocytes to others that as seen in this case, more closely resembles transformed mature B-cells. Well-fixed sections show more dispersed chromatin than mature small B-cells as seen in diffuse large cells lymphoma.
Immunophenotype: The lymphoblasts in B-LBL are often CD20 negative but positive for B-cell markers including CD19, CD22 (atleast cytoplasmic) and CD79a. They are also positive for PAX5, surface CD22 and CD24. Many cases show strong positivity for CD10, the 'common ALL antigen'. Most cases demonstrate variable expression for CD34 and TdT. CD45 expression is weak and not always detectable by immunohistochemistry. The myeloid-associated antigens CD13 and CD33 may also be expressed.
Prognosis: Patients with B-LBL have more favorable complete remission rate and duration, than with B-ALL treated with similar regimens. As with B-ALL, the prognosis of B-LBL is favorable in children than in adults. Most patients have normal serum LDH levels and no constitutional symptoms.
B lymphoblastic leukemia/lymphoma with recurrent genetic abnormalities: These lesions are associated with distinctive clinical or phenotypic properties, prognostic implications, and are generally mutually exclusive with other entities. Included in this category are:
t(9; 22); BCR-ABL1, t(v; 11q23)- poor prognosis
MLL rearranged- poor prognosis
t(12; 21)(p13;q22); TEL-AML1 (ETV6-RUNX1)- favorable prognosis
Hyperdiploidy- very favorable prognosis
Hypodiploidy- poor prognosis
t(5;14)(q31;q32); IL3-IGH - No change in prognosis
t(1;19)(q23;p13.3); E2A-PBX1(TCF3-PBX1)- poor prognosis
In our case limited fluorescent in-situ hybridization studies for t (9; 22) BCR-ABL1 were performed and was negative.
DLBCL-diffuse large B-cell lymphoma
MCL-mantle cell lymphoma
cCD3- cytoplasmic CD3
Contributed by Sarika Jain, MD and and Steven H Swerdlow, MD